ANSI C80.1-94 Rigid Steel Conduit Zinc Coated (GRC)

ANSI C80.1-1994

Rigid Steel Conduit-

Zinc Coated W C )

Natlonal Electrlcrl Manufacturers Assoclatlon

1300 North 17th Street Su i te 1847

Rosslyn, Virginia 22209 (703) 841 -3200

m National Standard th permission of the American resale. No part of this publication , electronic retrieval system or ission of the American National reet, New York, New York 10036.

-Amflas$ndard

COPYRIGHT American National Standards InstituteLicensed by Information Handling ServicesCOPYRIGHT American National Standards InstituteLicensed by Information Handling Services

ANSI" C80.1-1994

American National Standard

for Rigid Steel Conduit- Zinc Coated (GRC)

Secretariat National Electrical Manufacturers Association

Approved American National Standards Institution, Inc.

Abstract This standard has been developed to specify dimensions and weights for zinc-coated rigid steel conduit, elbows, couplings and nipples for use as an electrical raceway. Trade size designators (metric size designators) range from 1/2 (16 GRC) to 6 (155 GRC). Basic data for threads are included as well as requisite tests for mechanical properties of the conduit and for the zinc coating.


American Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and other criteria for approval have been National met by the standards developer.

Standard Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution.

The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards.

The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard.

CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of approval. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute.

Published by

National Electrical Manufacturers Association 1300 N. 17th Street, Rosslyn, Virginia 22209

Copyright O 1995 by American National Standards Institute, Inc. All rights reserved.

No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.

Printed in the United States of America APS5C291 /I 2


Contents

PAGE Foreword ......................................................................................................................................................... i 1 Scope .................................................................................................................................................. 1 2 Normative references ........................................................................................................................... 1 3 Definitions ............................................................................................................................................. 1

5 General requirements .......................................................................................................................... 1 4 Units of measurements ........................................................................................................................ 1

5.1 Circular cross section ................................................................................................................ 1 5.2 Wall thickness ............................................................................................................................ 1 5.3 Interior surface ........................................................................................................................... 2 5.4 Welding ...................................................................................................................................... 2 5.5 Cleaning ..................................................................................................................................... 2

6 Detailed requirements .......................................................................................................................... 2

6.2 Enamel or equivalent coating .................................................................................................... 2

6.4 Identification ............................................................................................................................... 2 6.5 Dimensions ................................................................................................................................ 2 6.6 Threads ...................................................................................................................................... 2

6.8 Elbows, bends and nipples ....................................................................................................... 3 7 Test procedures ................................................................................................................................... 3

7.1 Bending properties .................................................................................................................... 3

7.3 Quality of enamel coating for use on interior surfaces ............................................................. 4 8 Examination of product ........................................................................................................................ 4

8.1 Place of inspection .................................................................................................................... 4 8.2 Visual inspection ........................................................................................................................ 4 8.3 Restrictions on localized surface imperfections ........................................................................ 4 8.4 Retests ....................................................................................................................................... 4

9 Marking ................................................................................................................................................ 4

5.6 Protective coating ...................................................................................................................... 2

6.1 Zinc coating ............................................................................................................................... 2

6.3 Threading and chamfering ........................................................................................................ 2

6.7 Couplings ................................................................................................................................... 2

7.2 Thickness of zinc coating .......................................................................................................... 3

I


ANSI C80.1-1994

Foreword (This Foreword is not part of American National Standard C80.6-1994)

This standard was developed by the Accredited Standards Committee on Raceways for Electrical Wiring Systems, C80. The objective of the committee is to produce a comprehensive specification that would establish uniform dimensions and standard construction requirements for rigid metal conduit, electrical metallic tubing, intermediate metal conduit and rigid aluminum conduit raceway products and their associated components.

The standard was originally approved in 1950 and revised in 1953, 1959, 1963, 1966, 1977, 1983 and 1990.

Suggestions for improvement of this standard will be welcome. They should be sent to the National Electrical Manufacturers Association, 1300 N. 17th Street, Rosslyn, Virginia 22209.

This standard was processed and approved for submittal to ANSI by the Accredited Standards Cornmittee on Raceways for Electrical Wiring Systems, C80. Committee approval of the standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the C80 Committee had the following members:

J. A. Gruber, Chairman J. A. Gauthier, Secretary

Organization Represented

Aluminum Association American Iron and Steel Institute American Pipe Fittings Association International Association of Electrical Inspectors International Brotherhood of Electrical Workers

National Electrical Contractors Association National Electrical Manufacturers Association

Telephone Group Underwriters Laboratories, Inc.

Name of Representative

P.Pollak M.Palivoda R.T.Bryson

K.R.Edwards J.Widener

A.W.Ballard C.W.Beile D.Gearing J.A.Gruber J.H.Kuczka T.McNeive S.Schauffele R.Higgenbottom (Alt.) P.Horton (Alt.) R.Jazowski (Alt.) F.W.McGeehan G.Rusinski R.LaRocca (Alt.)

W.Lilly

C.H.Williams

II


AMERICAN NATIONAL STANDARD ANsl m.1-1994

American National Standard for Rigid S t e e l Conduit- Zinc Coated (GRC)

1 scope

The following standards contain provisions which, through r e f e r e n c e in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on ths Amerimn National standard are encouraged to investigate the possibinity of applying the most recent editions of the standards indicated bebw.

ANSVASME B1.20.1-1983 (R1992), P@ 7 7 ~ ~ ~ 3 , G e t ~ d R ~ ~ ( k h )

3 Definitions

3.1 Threaded coupling A threaded cwpling for rigid steel conduit is an internally threaded steel cylinder for oonnecting two sections oi rigid steel conduit.

3.3 Nipple A nipple is a straight section of rigid steel conduit threaded on each end.

4 Units of measurement

The values states in inchpoond units are to be regarded as the standard. The metric equivalents may be approximate.

5 Genera l requirements

5.1 Cirwkrcrosssection Rigid steel cmduit shall have a circular cross section sufticierrtly accurate to permit the cutting of threads in accordance with table 1.

5.2 Wall thickness The wall thidmess shall be uniform throughout except f o r localized surface imperfections as permitted in 8.3.

1


ANSI C80.1-1994

5.3 Interior surface The interior surface shall be free from injurious defects.

5.4 Welding The welding of all seams shall be continuous and done in a workmanlike manner.

5.5 Cleaning The conduit shall be adequately cleaned before the application of the protective coating. The cleaning process shall leave the exterior and interior surfaces of the conduit in such a condition that the protective coating shall be firmly adherent and smooth.

5.6 Protective coating

5.6.1 The exterior surface shall be thoroughly and evenly coated with metallic zinc applied directly to the surface of the steel so that metal-to-metal contact and galvanic protection against corrosion are provided.

5.6.2 The interior surface shall be protected by a zinc, enamel, or other suitable corrosion-resistant coating.

6 Detailed requirements

6.1 Zinc coating The zinc content of the coating on the outside surface shall be equivalent to a minimum thickness of 0.0008 in. (0.02 mm.)

6.2 Enamel or equivalent coating Enamel or other equivalent protective coating shall have a smooth continuous surface. An occasional variation due to uneven flow of coating shall be acceptable. The coating shall not soften at a temperature of 120F (49C) and shall be sufficiently elastic to meet the test described in 7.3.

6.3 Threading and chamfering Each length of conduit, nipple, elbow, and bend shall be threaded on both ends, and each end shall be chamfered or otherwise treated to remove burrs and sharp edges.

Threads shall comply with the requirements of 6.6. If threads are cut after the zinc coating has been applied, the threads shall be treated with a protective coating to prevent corrosion before installation. This treatment shall not impair electrical continuity through couplings or fittings after installation.

6.4 Identification Each length of conduit, nipple, elbow and bend shall be identified with the manufacturer's name or trademark and the words, "rigid steel conduit," except that close threaded nipples need not be so identified.

6.5 Dimensions The dimensions of Intermediate Metal Conduit shall be in accordance with table 2.

6.6 Threads The number of threads per inch (25.4 mm), and the length of the threaded portion at each end of each length of conduit, nipple, elbow and bend shall be as indicated in table 1, and shall conform to ANSVASME B1.20.1- 1983 (R1992). The perfect thread shall be tapered for its entire length, and the taper shall be 3/4 in/ft (62.5 I mdm).

6.7 Couplings Couplings shall comply with the following requirements.

2


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STD.ANSI C B O - 1 - E N G L L774 SB 0 7 2 4 3 5 0 0 5 4 2 3 7 9 457

ANSI C80.1 -1994

6.7.1 The exterior surface of couplings shall be protected by means of a zinc coating, which shall comply with the requirements of 6.1. The interior surface shall be treated to inhibit corrosion from taking place prior to installation.

6.7.2 Couplings shall be so made that all threads on the conduit will be covered when the coupling is pulled tight on standard conduit threads.

6.7.3 Both ends of the coupling shall be chamfered to prevent damage to the starting thread.

6.7.4 The outside diameter, length, pitch diameter, and chamfer diameter of couplings shall be as indicated in table 3.

6.7.5 Couplings shall be straight tapped.

6.7.6 Each length of finished conduit shall have one coupling attached.

6.8 Elbows, bends and nipples Conduit elbows, bends and nipples shall be made of a similar grade of steel to that employed in straight lengths of rigid steel conduit, and shall be treated, coated, threaded, and marked for identification according to the applicable requirements for rigid steel conduit (zinc coated). The dimensions of 90-degree elbows and the weights of nipples shall be as indicated in table 4.

7 Test procedures

7.1 Bending properties

7.1.1 Ductility of steel Conduit shall be capable of being bent cold into a quarter of a circle around a mandrel, the radius of which is shown in table 4, without developing cracks at any portion and without opening the weld.

7.1.2 Ductility of zinc coating. The protective coatings used on the exterior and interior surfaces of rigid steel conduit shall be sufficiently elastic to prevent their cracking or flaking off when a finished sample of trade size designator 1/2 (16 GRC) or the smallest trade size manufactured is tested. Test shall be performed within 1 year after the time of manufacture, by bending 1/2 (16 GRC) into a half-circle around a mandrel, the radius of which is shown in table 4 or by bending other trade size designators into a quarter-circle around a mandrel, the radius of which is shown in table 4.

Compliance of trade size designators 1/2 (16 GRC) and 3/4 (21 GRC) shall be determined by bending the conduit with a form as shown in figure 1. Compliance of trade size designators larger than 3/4 (21 GRC) shall be determined by bending the conduit with any suitable bending equipment.

7.2 Thickness of zinc coating One of the following test methods shall be employed for measuring the thickness or extent of the external zinc coating on conduit:

- Magnetic test - Preece test (material that will withstand four 1 -minute immersions shall be considered as meeting the

requirements of 6.1.

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ANSI C80.1-1994

"""

W

Figure 1 - Form for bending tubing

4


~

STD.ANSI C B O - L - E N G L w t 4 m 0 7 2 4 3 5 0 0 5 w m , 9 3 5 n

ANSI C80.1 -1994

7.3 Quality of enamel coating for use on interior surfaces Test pieces of uncoated sheet steel, 3 in.(76.2 mm) wide, 5 in.(127.00 mm) long, and 0.010 in.(0.25 mm) thick, shall be cleaned with a suitable solvent to remove all grease and foreign material. Each piece shall be dipped into the enamel that is used for coating the conduit and the coated test pieces shall be allowed to air- dry for 30 minutes before being placed in the baking oven. Each piece shall be suspended by means of short wires in the baking oven and the samples shall be baked for a period of 5 hours at the normal baking temperature for the enamel in question, except that if the normal baking temperature is less than 275F (135C) or if the enamel is regularly air-dried, the oven temperature shall be maintained at 275F to 302F (1 35C to 150C).

At the end of the 5-hour period, the test samples shall be removed from the oven and allowed to air-cool to room temperature. Each test piece shall be gripped in a vise and then bent from the opposite side back and forth ten times through an angle of 180 degrees, the radius of the bend being 1/16 in. (1.59 mm). When so tested, the enamel coating on the sample shall not crack or flake.

8 Inspection

8.1 Place of inspection All tests and inspections shall be made at the place of manufacture prior to shipment, unless otherwise specified, and shall be so conducted as not to interfere with normal manufacturing processes.

8.2 Visual inspection Each length of conduit shall be examined visually, both on the exterior and interior surfaces to determine if the product is free from slivers, burrs, scale, or other similar injurious defects, and if coverage of the coating is complete.

8.3 Restrictions on localized surface imperfections Localized surface imperfections may not exceed a depth of 12-112%.

8.4 Retests If any sample tested as prescribed in this specification should fail, two additional samples shall be tested, both of which shall comply with the requirements of this specification.

9 Marking

9.1 Identification Each length of conduit, nipple, elbow and bend shall be identified with the manufacturer's name or trademark and the letters IMC at least 1/8 in.(3 mm) high, except that close threaded nipples need not be so identified.

5


STD-ANSI C B D - 1 - E N G L L774 0 7 2 4 1 5 0 0542402 871

ANSI C80.1-1994

Table 1 - Dimensions of threads for rigid steel conduit 1

Trade Size

Designator

112 314 1

1-114 1-112 2

2-112 3

3112 4 5

Custom

Threads

Per ln.

14 14

11-112 11-112 11-112 11-1/2 8 8 8 8 8

Inch-Pou1 Pitch

diameter at end of thread

Eo, taper 3/4 in. per ft.

0.7584 0.9677 1.21 36 1.5571 1.7961 2.2690 2.71 95 3.3406 3.8375 4.3344 5.3907 6.4461 "-L

NOTE- Applicable tolerances:

Units

Length of Thread (In.)

Effective

L, 0.53 0.55 0.68 0.71 0.72 0.76 1.14 1.20 1.25 1.30 1.41 1.51

Overall

L4

0.78 0.79 0.98 1 .o1 1 .O3 1 .o6 1.57 1.63 1 .Ea 1.73 1.84 1.95

Metric Units Pitch

diameter at end of thread E,,

Trade Threads taper 62.5 Size per 25.4 mm. per

Designator meter mm.

16 GRC 14

163.731 8 155 GRC 136.924 8 129 GRC 11 0.094 8 103 GRC 97.473 8 91 GRC 84.851 8 78 GRC 69.075 8 63 GRC 57.633 11-112 53 GRC 45.621 11-112 41 GRC 39.550 11-112 35 GRC 30.825 1 1-112 27 GRC 24.580 14 21 GRC 19.263

Length of Thread (mm)

Effective

4 13.46 13.97 17.27 18.03 18.29 19.30 28.96 30.48 31.75 33.02 35.81 38.35

Thread length (L4): fl thread, recommended practice +O, -1 Pitch diameter: -+1 turn is the maximum variation permitted from the gaging face of the working thread gauges.

Table 2 - Dimensions and weights of rigid steel conduit

Overall

14 19.81 20.07 24.89 25.65 26.16 26.92 39.88 41.40 42.67 43.94 46.74 49.53

I

I Trade Size Nominal Inside Designator Diameter (in.)

112

6.093 6 5.073 5 4.050 4 3.570 3-112 3.090 3 2.489 2- 1 12 2.083 2 1.624 1-112 1.394 1-114 1 .o63 1 0.836 314 0.632

Outside Diameter (in.)

0.840

I Nominal Wall * Thickness in. 1 .O50 1.31 5 1.660 1 .goo 2.375 2.875 3.500 4.000 4.500 5.563 6.625

Metric Trade Outside Diameter Nominal Inside Size Designator

16 GRC 21 GRC 27 GRC 35 GRC 41 GRC 53 GRC 63 GRC 78 GRC 91 GRC 103 GRC 129 GRC 155 GRC

Diameter (mm) I (mm) 16.1 I 21.3 21.2

48.3 41.2 42.2 35.4 33.4 27.0 26.7

168.3 154.8 141.3 128.9 114.3 102.9 101.6 90.7 88.9 78.5 73.0 63.2 60.3 52.9

0.1 07 0.126

0.138 0.146 0.1 93 0.205 0.215

0.245 0.266

Units

Nominal Wall Thickness (mm)

2.64 2.72 3.20 3.38 3.51 3.71 4.90 5.21 5.46 2.72 6.22 6.76

Minimum Weight of Length Without

Attached (Ib.) (ft. and in.) with Couplings Coupling

Ten Unit Lengths

9'1 1-114"

1745.3 9'1 o" 1313.6 9'1 o" 972.3 9'10-114 831 .O 9'10-114 682.6 910-112" 527.0 9'10-112" 332.0 9'1 1" 249.0 9'1 1" 201 .o 9'1 1" 153.0 9'1 1" 105.0 9'1 1-114 79.0

Length Without Coupling Meters

3.03 3.03 3.02 3.02 3.02 3.02 3.01 3.01 3.00 3.00 3.00 3.00

~ Minimum Weight of Ten Unit Lengths With Couplings Attached (kg)

35.83 47.63 69.40 91.17 112.95 150.60 239.05 309.63 376.94 441 .W 595.85 791.67

6


NOTE-Applicable tolerances: Length: f114 in. (6.35 mm) (without coupling) Outside Diameter:

for trade sizes 112 (16 GRC) through 2 (53 GRC): M.015 in. (M.38 mm) for trade sizes 2-112 (63 GRC) through 4 (103 GRC: M.025 in. (kO.64 mm) for trade sizes 5 (129 GRC) and 6 (155 GRC): kl%

Wall Thickness: See 8.3

Table 3 - Dimensions of Couplings

Trade Size Designator

1 12 34 1

1-114 1-112 2

2- 1 12 3

3-1/2 4 5 6

Outside D Maximum 1.010 1.250 1.525 1.869 2.155 2.650 3.250 3.870 4.500 4.875 6.000 7.200

Minimum Maximum

1-41/64 1 -31 I32 2-1132 2-1/16 2-118 2-31 6 2-511 6 3-1 3/32 3-33/64 3-61/64 4-114

Outside Diameter Trade Size

41.3 25.7 16 GRC (mm) (mm) Designator

Minimum Maximum

21 GRC 31.8 41.7 27 GRC 38.7

108 182.9 155 GRC 1 O0 152.4 129 GRC 89.3 123.8 103 GRC 86.5 1 14.3 91 GRC 84.1 98.3 78 GRC 81 .O 82.6 63 GRC 54.0 67.3 53 GRC 52.4 54.7 41 GRC 51.6 47.5 35 GRC 50.0

NOTES 1 Outside diameter tolerances:

plus tolerances: no requirements minus tolerances-

i 3.431 1 .o1 1 1.267 1.612 1.852 2.327 2.806 3.931 4.431 5.494 6.556

Metric 1 Pitch I

Maximum (mm) 20.35 25.68 32.18 40.94 47.04 59.1 1 71.27 87.15 99.85 11 2.60 139.60 166.50

>und Units meter

Minimum 0.814 1 .O24 1.283 1.628 1.868 2.343 2.828 3.453 3.953 4.453 5.516 6.578

Chamfel Minimum (in.)

0.798 1 .O08 1.260 1.605 1 .W 2.320 2.800 3.425 3.925 4.425 5.519 6.591

iameter Maximum (in.)

0.838 1 .O48 1.300 1.645 1.885 2.360 2.860 3.485 3.985 4.485 5.579 6.651

its meter Chamfer Diameter

Minimum

168.90 167.40 167.10 141.70 140.20 140.10 113.90 112.40 113.10 1 01.20 99.70 100.40 88.52 87.00 87.71 72.64 71.12 71.83 59.94 58.93 59.51 47.88 46.86 47.45 41.78 40.77 41.35 33.02 32.00 32.59 26.62 25.60 26.01 21 -29 20.27 20.68 (mm) (mm) (mm)

Maximum Minimum

for trade sizes smaller than 1-114 (35 IMC): -1164 in. (-0.40 mm) for trade sizes 1-1/4 (35 IMC) and larger: 1%.

2 Chamfer angle shall be between 1 1 and 15 degrees. 3 All couplings shall have straight-tapped threads.

7


r

ANSI C80.1-1994

Table 4 -Dimensions of 90-Degree Elbows and Weights of Nipples per Hundred 1

Trade Size

Designator 1 12 3 4 1

1-114 1-112

2 2-112

3 3-112

4 5 6

4-1 12 5-Y4 7-1 I4 8-114 9-112 10-112

13 15 16 24 30

1-112 1 -7/8

2 2 2 3

3-1 I8 3-1 I4 3318 3-518 3-314

0.086 0.125 0.164 0.202 0.269 0.430 0.561 0.663 0.786 1 .O60 1.41 O

4 9 10 11 14 60 70 90 115 170 200

Customary InchPound Units Metric Units

Minimum Minimum

Center of Metric Length L, Center of Radius to Straight Radius to Minimum

(in-) End (in.) Lb. Lb. Designator 1 01.60 16 GRC 2 0.065 1-112 4 (mm)

Elbows Elbol Nipples

Conduit Conduit Trade Size B A at Each

21 GRC 27 GRC 35 GRC 41 GRC 53 GRC 63 GRC 78 GRC 91 GRC 103 GRC 129 GRC

' 155GRC

114.30 146.05 184.15 209.55 241.30 266.70 330.20 381 .O0 406.40 609.60 762.00

Ns Minimum Straight

Length Ls at Each

kg End (mm) A

38.10

0.640 95.25 0.481 92.08 0.357 85.73 0.301 82.55 0.254 79.38 0.1 95 76.20 0.1 22 50.80 0.092 50.80 0.074 50.80 0.057 47.63 0.039 38.1 O 0.029

les

B kg

0.91 1 .a1 4.08 4.54 4.99 6.35 27.22 31.75 40.82 52.1 6 77.1 1 90.72

NOTE-Each lot of 100 nipples shall weigh not less than the number of pounds (kilograms) determined by the formula: W=lOO*(LA)-B where: W is the weight of 100 nipples in pounds (kilograms) L is the length of one nipple in inches (millimeters) A is the weight of nipple per inch (25.4 mm) in pounds (kilograms) B is the weight in pounds (kilograms) lost in threading 100 nipples

8


Foreword1 Scope2 Normative references3 Definitions4 Units of measurements5 General requirements5.1 Circular cross section5.2 Wall thickness5.3 Interior surface5.4 Welding5.5 Cleaning5.6 Protective coating

6 Detailed requirements6.1 Zinc coating6.2 Enamel or equivalent coating6.3 Threading and chamfering6.4 Identification6.5 Dimensions6.6 Threads6.7 Couplings6.8 Elbows bends and nipples

7 Test procedures7.1 Bending properties7.2 Thickness of zinc coating7.3 Quality of enamel coating for use on interior surfaces

8 Examination of product8.1 Place of inspection8.2 Visual inspection8.3 Restrictions on localized surface imperfections8.4 Retests

9 Marking

Documents

ANSI C80.1-94 Rigid Steel Conduit Zinc Coated (GRC)